In the drama, Yoo Deok-hwan plays Han Zhenyu, a specially appointed forensic doctor at Korea University. According to the plot setting, after the end of the fourth season, Han Zhenyu will live a secluded life in the mountains near Gyeonggi Province. In this series, the cases seem to be perfect natural deaths or accidental deaths at first glance, but only the forensic doctor Han Zhenyu has a keen eye and can find clues from the mysterious murder case, clear away the layers of fog, and find the truth of the case.